Railcar bodyshells made of stainless steel, aluminum, or the like have been conventionally known. As a roof board of a roof bodyshell of a railcar or a floor panel of an underframe of the railcar, a corrugated panel (hereinafter referred to as a “thin wavy plate”) which has a wave-shaped cross section and is small in thickness is used to reduce the weight of the railcar while maintaining the strength thereof. Conventionally, weak portions of the roof bodyshell and underframe of the railcar have been reinforced by, for example, welding of reinforcing plates so as to be increased in stiffness. However, in a case where the weak portion to be reinforced is a part of the thin wavy plate, it is difficult to join a reinforcing member to the weak portion by welding or bolts. For example, in the case of the welding, one problem is that manufacturing accuracy deteriorates by thermal distortion, and in the case of the bolts, another problem is that a bolt hole is damaged and this deteriorates seal performance (hereinafter referred to as “water-tightness”) for preventing the ingress of water. Further, yet another problem is that the weights of the roof board and the floor panel increase by reinforcement.
Here, each of PTLs 1 to 4 proposes a technique to use a carbon fiber reinforced resin for the outside plate and frame member of the railcar. In accordance with these techniques, the railcar bodyshell can be significantly reduced in weight.